Up until a few weeks ago, I only had 2 boy quail. We kept them in separate cages, but would take them outside most days and so I set up some runs for them. The boys love love love being outside, and they do indeed tear up the grass wherever they are. I also put their runs in the garden a lot this summer, and showed them how to get cabbage worms off my cabbages, and tried to teach them to dig for worms (they didn't do it naturally, and never quite picked up on it). The runs I made them are simply hardware cloth, bent into a tunnel shape. I use landscaping cloth anchoring pins to hold the runs down firmly on the ground, but can move them easily. Only problem is that this is a very imperfect arrangement. I've had quail escapes and hawk attacks. Right now, I haven't put the boys outside for a week, after the last hawk attack, I feel the boys need something safer than their cages.
I would love to do a tractor, and asked my husband to build some, but he didn't get around to it, so I ended up buying a used rabbit hutch when I bought a bunch of hens recently. I'm not entirely thrilled with the hutch solution, because it is a bit too big to be portable like a tractor, and I'm not really wanting to leave it in one spot. We will be creating a run for the coop, and eventually bringing the boys to live with the new girls. They won't be moving into the coop with the girls for a little while--the main roo for the hens was the one injured by the hawk, so he needs to heal for a while.